<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        ul,
        li {
            list-style: none;
        }

        ul {
            display: flex;
            justify-content: space-around;
            width: 600px;
        }

        li {
            width: 80px;
            height: 40px;
            line-height: 40px;
            border: 1px solid orangered;
            background: orange;
            color: #fff;
            font-size: 20px;
            text-align: center;
        }
    </style>
</head>

<body>
    <ul>
        <li title="a">1</li>
        <li title="b">2</li>
        <li title="c">3</li>
        <li title="d">4</li>
        <li title="e">5</li>
        <li title="f">6</li>
        <li title="g">7</li>
    </ul>
    <audio src=""></audio>
    <script>

        var oA = document.querySelector('audio');
        var aLi = document.querySelectorAll('li');
        for (var i = 0; i < aLi.length; i++) {
            aLi[i].onmouseover = function () {
                console.log(this.title);
                var au = document.createElement('audio');
                document.querySelector('body').appendChild(au);
                au.src = 'http://s8.qhimg.com/share/audio/piano1/' + this.title + '4.mp3';
                au.autoplay = "autoplay";
            }
        }
    </script>
</body>

</html>